ELISP is a pretty fast language, faster than VimScript or JS for sure.
EDIT: Also, Emacs is bloated is bloated because it's not just a editor its's an Web Browser, Email Client, News Reader, Music Player and File Manager. If people want a light emacs, they can go use uEmacs or become the last JEDi.
This comment is the exact reason a text internet is still needed, because otherwise it will turn into a lag fest full of strange Javascript frameworks just to show a single article.